1. Field of the Invention
Embodiments of the present invention generally relate to a cooled shield used in a physical vapor deposition (PVD) system.
2. Description of the Related Art
PVD using a magnetron is one method of depositing material onto a substrate. During a PVD process a target may be electrically biased so that ions generated in a process region can bombard the target surface with sufficient energy to dislodge atoms from the target. The process of biasing a target to cause the generation of a plasma that causes ions to bombard and remove atoms from the target surface is commonly called sputtering. The sputtered atoms travel generally toward the substrate being sputter coated, and the sputtered atoms are deposited on the substrate. Alternatively, the atoms react with a gas in the plasma, for example, nitrogen, to reactively deposit a compound on the substrate. Reactive sputtering is often used to form thin barrier and nucleation layers of titanium nitride or tantalum nitride on the substrate.
Direct current (DC) sputtering and alternating current (AC) sputtering are forms of sputtering in which the target is biased to attract ions towards the target. The target may be biased to a negative bias in the range of about −100 to −600 V to attract positive ions of the working gas (e.g., argon) toward the target to sputter the atoms. Usually, the sides of the sputter chamber are covered with a shield to protect the chamber walls from sputter deposition. The shield may be electrically grounded and thus provide an anode in opposition to the target cathode to capacitively couple the target power to the plasma generated in the sputter chamber.
During sputtering, material may sputter and deposit on the exposed surfaces within the chamber. As chamber components are moved, material that has been deposited thereon may flake off and contaminate the substrate. As temperatures fluxuate from a processing temperature to a lower, non-processing temperature, material may additionally flake off of a moving component.
When depositing thin films over substrates such as wafer substrates, glass substrates, flat panel display substrates, solar panel substrates, and other suitable substrates, flaking may contaminate the substrate. Therefore, there is a need in the art to reduce flaking in PVD chambers.